1. Field of the Invention
The present invention relates to 5-fluorouracil derivatives and, more particularly, to novel 1-carbamoyl-5-fluorouracils represented by the formula ##STR2## wherein R.sub.1 represents methyl, ethyl, phenyl or cyclohexyl and R.sub.2 represents hydrogen or is the same as R.sub.1.
2. Description of the Prior Art
5-Fluorouracil is well known to be an effective anti-metabolite used as an anti-tumor agent. However, due to its high toxicity, 5-fluorouracil is not considered to be a favorable anti-tumor agent and improvement has been recognized as necessary. On the other hand, as a low toxic 5-fluorouracil derivative, there is known 5-fluoro-1-(2-tetrahydrofuryl)uracil which has been used as an anti-tumor agent. However, this compound is substantially inferior to 5-fluorouracil in anti-tumor activity and it has been desired to develop 5-fluorouracil derivatives which are as non-toxic as 5-fluoro-1-(2-tetrahydrofuryl)uracil and are also substantially more effective anti-metabolites.